Abstract:Polymer solid electrolytes are getting important for various electrochemical device applications, due to their high ionic conductivity, high mechanical and thermal stability. In the PEO polymer solid electrolyte, the transport of Li+ cations are coupled with the local relaxation and segmental motion of the PEO chains and better transport of Li+ ions can occur when PEO is in its amorphous state.The present paper reports the synthesis of La2O3 nano particles by sol gel foam combustion route and the prepared La2O3 nano particles are suspended in the polyethylene oxide + LiClO4 + MoO3 to form the nano composite polymer solid electrolyte film by the solution casting route.